Risers, which are fluid-carrying conduits, are widely used in the production and transfer of hydrocarbons in offshore installations, such as to carry oil and/or gas from a sea floor well up to a vessel that floats at the sea surface. The connection and disconnection of the ends of risers can be time-consuming. One current method is to mount an enlargement on the riser near an upper end of the riser. The vessel carries a basket that can hold the enlargement. The riser is lifted until the enlargement lies above the level of the basket. The riser is moved sideward through a slot in the basket so the enlargement is directly over the basket. The enlargement is then lowered until it lies nested in the basket. Thereafter, the basket supports the enlargement and the upper end of the riser. This method is time consuming. In some situations, as where the riser upper end must be pulled up into an underwater opening in a turret of the vessel, considerable extra space must be provided, in addition to the awkwardness of shifting the enlargement through the slot before setting it down into the basket. It is desirable that no separate hydraulic or electrical actuator be required to latch the enlargement in the basket. A way of latching a lifted riser enlargement into a receptacle on a vessel, which minimizes the required space around the receptacle, which can be easily operated, and which does not require electric or hydraulic energized locks, would be of value.